Throttle bodies with throttle valves actuated by motors

ABSTRACT

A throttle body ( 1 ) includes a throttle casing ( 2 ) and a motor casing ( 8 ). The throttle casing has a first main body ( 3 ) and a throttle valve ( 4 ) disposed within the first main body. The first main body is made of resin. The motor casing ( 8 ) has a second main body ( 9 ) and a motor ( 11 ) disposed within the second main body. The first main body and the second main body are formed separately from each other and are connected to each other via a joint device ( 27 ).

[0001] This application claims priority to Japanese patent applicationserial number 2002-361477, the contents of which are incorporated hereinby reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to throttle bodies that havethrottle valves actuated by motors for controlling the rotational speedof internal combustion engines.

[0004] 2. Description of the Related Art

[0005] There are known throttle bodies that have motor actuated throttlevalves. For example, Japanese Laid-Open Patent Publication No.2001-132495 teaches a throttle body in which a throttle valve, athrottle shaft, a motor, a gear mechanism, and a throttle sensor, aredisposed. The throttle valve is secured to the throttle shaft and themotor rotatably drives the throttle shaft. The gear mechanism serves totransmit the driving force of the motor to the throttle shaft. Thethrottle sensor serves to detect a degree of opening of the throttlevalve.

[0006] Additionally, in recent years in order to reduce the weight andthe manufacturing costs of an automobile, there has been a tendency touse materials such as resin in the fabrication of automobiles parts,possibly including such parts as throttle bodies.

[0007] However, in the case of throttle bodies made of resin, there is apossibility that some problems may be caused by this material selection.These problems will be explained with reference to FIG. 4.

[0008] A conventional throttle body 61 is shown in FIG. 4 and includes amain body 62. The main body 62 has a bore wall portion 62 a that definesan intake air channel, in which a throttle valve 5 is disposed. The mainbody 62 also defines a space for receiving a motor 11. In the case wherethe main body 62 is made of resin, the heat produced by the motor 11 maynot be effectively dissipated to the outside of the main body 62, due tothe low heat conduction efficiency of the material. Therefore, there isa possibility of overheating and damaging the motor 11. In addition,because the heat may not be effectively dissipated, the bore wallportion 62 a may be thermally deformed and cause unwanted interferencewith the throttle valve 5. In such a situation, the controllability ofthe throttle valve 5 may be lessened. Further, if a molding process,such as an injection molding process, forms the main body 62, there is apossibility that attaining the substantial circularity of the intake airchannel will be inhibited due to the variations in the thickness of thebore wall portion 62 a along the circumferential length of the intakeair channel. The resulting bore wall portion 62 a due to moldingconditions may also cause unwanted interference with the throttle valve5.

SUMMARY OF THE INVENTION

[0009] It is accordingly an object of the present invention to teachimproved techniques for ensuring the substantial circularity of anintake air channel when a lightweight and/or low cost material, such asresin for example, is used in the fabrication of a throttle body.

[0010] According to one aspect of the present teachings, throttle bodiesare taught which include a throttle casing. The throttle casing includesa first main body in which a throttle valve is disposed. The first mainbody is made of a synthetic resin, e.g., ABS resin, by using anappropriate molding process, such as an injection molding process forexample. The first main body may be formed as an individual component.Another component, a motor casing, includes a second main body, mayaccommodate a motor and/or a gear mechanism and/or a throttle sensor,within the second main body. The first main body is connected to thesecond main body via a joint device, e.g., screws, rivets, spring clips,snap connections, etc.

[0011] The first main body has a relatively simple structure and thefreedom of design unencumbered by the constraints of additionalfunctions. The first main body can be individually designed in order toreduce or minimize the residual molding stresses and strains that may becaused by substantial variations in molded wall thickness. In addition,because the first main body of the throttle casing is a componentseparate from the second main body of the motor casing, the unwantedconduction of heat from the motor to the bore wall portion duringthrottle valve operation can be reduced. Interposing an appropriate heatinsulation material between the first main body and the second main bodycan further minimize the unwanted conduction of heat.

[0012] An additional aspect of the present invention has a throttle bodywherein the first main body includes a substantially cylindrical boreportion that defines a flow channel. Disposed within the flow channel isthe throttle valve. The cylindrical bore portion has a substantiallyuniform thickness in the circumferential direction.

[0013] The potential deformation of the throttle casing due to eitherresidual molding stress and/or strain, or due to the conduction of heatfrom the motor, can be reduced or minimized. This allows the substantialcircularity of the inner wall of the bore portion to be more easilymaintained and controlled, resulting in a reduction in unwantedinterference with the throttle valve during normal operating conditions.

[0014] According to another aspect of the present teachings, the motorcasing can be made of a high thermal conductivity material, e.g., suchas metal for example. Preferably, the metal may be lightweight metal,e.g., examples such as aluminum or aluminum alloy. Therefore, the heatof the motor may be effectively dissipated directly to the outside ofthe motor casing, causing a further reduction in the conduction of motorgenerated heat to the throttle casing.

[0015] In another aspect of the present teachings, the throttle bodiesfurther include a coupling device for coupling the throttle valve to themotor. Therefore, the rotation of the motor can be transmitted to thethrottle valve via the coupling device. Preferably, the coupling devicecouples the throttle valve to the motor at the same time that the firstmain body and the second main body are connected to each other via thejoint device.

[0016] In still another aspect of the present teachings, the throttlecasing further includes a throttle shaft that is rotatably disposedwithin the first main body and the throttle valve is mounted on thethrottle shaft. The motor casing further includes a gear mechanism fortransmitting rotation of the motor to the throttle shaft. Thus, themotor casing also serves as a gear casing. The coupling device serves tocouple the throttle shaft to the gear mechanism.

[0017] In a further aspect of the present teachings, the gear mechanismincludes a drive shaft that extends from the second main body. Thecoupling device includes a recess and a projection that is formed on oneand the other of the drive shaft and the throttle shaft and isengageable with each other for transmitting rotation of the drive shaftto the throttle shaft.

[0018] In another aspect of the present teachings, the throttle bodyfurther includes a cover that has a third main body that is formedseparately from the first main body and the second main body. The thirdmain body is mounted on the second main body in order to cover the motorand associated elements, e.g., the gear mechanism, from the outside ofthe motor casing. Therefore, the motor casing and the cover can beassembled into a subassembly that has the motor and the gear mechanismdisposed therein. The throttle casing may then be connected to the motorcasing of the subassembly. Preferably, the third main body is made ofmetal, in particular a lightweight metal, such as for example, aluminumor aluminum alloy among others, so that the heat of the motor can alsobe efficiently dissipated from the cover.

[0019] In still another aspect of the present teachings, a seal device,e.g., possibly an O-ring, is interposed between the first main body andthe second main body in order to provide a seal there between.Therefore, any dust or unwanted foreign particles are inhibited fromentering and possibly damaging the internal elements of the throttlebody (e.g., the throttle valve, the motor, the gear mechanism, athrottle sensor, etc.). As a result, the internal elements are protectedin order to operate reliably in the performance of their individualfunctions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a cross sectional view of a representative throttle bodyaccording to the present invention; and

[0021]FIG. 2 is an exploded view of FIG. 1; and

[0022]FIG. 3 is a side view of the throttle body as viewed in thedirection of arrow P in FIG. 1; and

[0023]FIG. 4 is a cross sectional view of a conventional throttle body.

DETAILED DESCRIPTION OF THE INVENTION

[0024] Each of the additional features and teachings disclosed above andbelow may be utilized separately or in conjunction with other featuresand teachings to provide improved throttle bodies and methods of usingsuch throttle bodies. Representative examples of the present invention,which examples utilize many of these additional features and teachingsboth separately and in conjunction, will now be described in detail withreference to the attached drawings. This detailed description is merelyintended to teach a person of skill in the art further details forpracticing preferred aspects of the present teachings and is notintended to limit the scope of the invention. Only the claims define thescope of the claimed invention. Therefore, combinations of features andsteps disclosed in the following detailed description may not benecessary to practice the invention in the broadest sense, and areinstead taught merely to particularly describe representative examplesof the invention. Moreover, various features of the representativeexamples and the dependent claims may be combined in ways that are notspecifically enumerated in order to provide additional usefulembodiments of the present teachings.

[0025] A representative embodiment will now be described with referenceto FIGS. 1 to 3. A representative throttle body 1 includes threeseparate members, i.e., a throttle casing 2, a motor/gear casing 8, anda cover 20, that are formed individually and assembled into the throttlebody 1.

[0026] Referring to FIGS. 1 and 2, the first member, the throttle casing2, has an integral first main body 3 that is made of synthetic resin,e.g., ABS resin. The first main body 3 may be formed by an injectionmolding process. A cylindrical bore portion 3 a is disposed within thefirst main body 3 and defines an intake air channel. A throttle valve 5is disposed within the intake air channel. A throttle shaft 4 extendsacross the intake air channel and is rotatably supported via tubularsleeves 3 a 1 and 3 a 2. The tubular sleeves 3 a 1 and 3 a 2 extend fromopposing sides of the bore portion 3 a in a diametrical direction. Thethrottle valve 5 is secured to the throttle shaft 4 via fasteningdevices, in this case, screws 6. A recess 4 a is formed in an endsurface of an end (the right end as viewed in FIG. 1) of throttle shaft4 that terminates within the tubular sleeve 3 a 2. The recess 4 a servesto engage a drive shaft 16 that will be explained later. The other endof the throttle shaft 4 terminates within the tubular sleeve 3 a 1. Aseal plug 7 is press-fitted into the end (the left end as viewed inFIG. 1) of tubular sleeve 3 a 1 in order to inhibit communicationbetween the inner space of the tubular sleeve 3 a 1 and the outsideenvironment.

[0027] A first flange 3 b extends in an outward radial direction fromthe tubular sleeve 3 a 2, i.e., perpendicular to the axis of thethrottle shaft 4. The first flange 3 b is adapted to secure themotor/gear casing 8 to the throttle casing 2. A second flange 3 c isdisposed at one axial end of the bore portion 3 a and extends in anoutward radial direction from bore portion 3 a. The second flange 3 c isadapted to secure the throttle casing 2 to an intake manifold of aninternal combustion engine (not shown).

[0028] The bore portion 3 a has a substantially uniform thickness alonga circumferential direction. In addition, each of the first and secondflanges 3 b and 3 c also have a substantially uniform thickness.Therefore, any residual stress and/or strain created by the moldingprocess can be minimized.

[0029] Referring to FIGS. 1 and 2, the second individual member, themotor/gear casing 8 of throttle body 1, has a second main body 9 made ofa thermally conductive material. For example, such a material may be ametal, in particular a lightweight metal, preferably aluminum oraluminum alloy. The second main body 9 has a cylindrical portion 9 athat is closed at one end (the left end as viewed in FIG. 2). A motor 11is disposed within the cylindrical portion 9 a and is biased along anaxial direction by a biasing means, in this drawing a leaf spring 10 isshown. The motor 11 has an integral bracket 11 a that is fixed to thesecond main body 9 via fastening devices, such as bolts 12 (see FIG. 3).A drive gear 13 is fixed to an output shaft 11 b of the motor 11, sothat the drive gear 13 rotates in the same direction and rotationalspeed of output shaft 11 b.

[0030] A gear shaft 14 is press-fitted into a corresponding fitting holeformed in the second main body 9. An intermediate gear 15 is rotatablymounted on the gear shaft 14. The intermediate gear 15 can be fixedalong the axial direction relative to the gear shaft 14 by a third mainbody 21 of the cover 20 that is mounted to the second main body 9 of themotor/gear casing 8, as will be explained later.

[0031] A drive shaft 16 is rotatably supported within the second mainbody 9. A throttle gear 17 is mounted on the drive shaft 16, such thatthe drive shaft 16 rotates in the same direction and at the samerotational speed as the throttle gear 17. The throttle gear 17 isconfigured as a sector gear.

[0032] A projection 16 a extends from one end (left end as viewed inFIG. 2) of the drive shaft 16 a and is engageable with the recess 4 a ofthe throttle shaft 4, so that the throttle shaft 4 can rotate in thesame direction and at the same rotational speed as the drive shaft 16 a.The recess 4 a and the projection 16 a may have a D-shaped crosssection. Alternatively, the recess 4 a and the projection 16 a may havea polygonal cross sectional configuration.

[0033] A biasing device, shown as a torsion coil spring 18, is disposedwithin the second main body 9 and serves to bias the throttle valve 5 inthe closing direction. To achieve this result, one end of the torsioncoil spring 18 is attached to the throttle gear 17. The other end of thetorsion coil spring 18 is attached to the second main body 9. Thetorsion coil spring 18 biases the throttle valve 5 via the throttle gear17 towards a fully closed position of the throttle valve 5.

[0034] Magnets 19 are fitted into the throttle gear 17 in positionsfacing a throttle sensor 22, throttle sensor 22 will be explained later.The intermediate gear 15 has a large gear portion 15 a and a small gearportion 15 b that respectively engage the drive gear 13 and the throttlegear 17. The engagement of the gears causes the rotational speed of themotor 11 to be transmitted at a reduced level to the throttle gear 17.The rotation of the throttle gear 17 is then directly transmitted to thethrottle valve 5 via the drive shaft 16. As a result, the throttle valve5 is opened and closed as the motor 11 rotates in one direction and adirection opposite thereto, respectively.

[0035] Referring to FIGS. 1 and 2, the third separate member, the cover20, has a third main body 21 that is made of a lightweight, highthermally conductive material such as metal, preferably aluminum oraluminum alloy similar to the material of the second main body 9 of themotor/gear casing 8. The throttle sensor 22 is mounted on the third mainbody 21 in a position facing the magnets 19 that are fitted into thethrottle gear 17. The sensor 22 is electrically connected to anelectrical control unit (ECU) (not shown) that serves to control theoperation of the engine in a known manner.

[0036] A boss portion 21 b is formed on the third main body 21 in aposition facing the gear shaft 14. The boss portion 21 b has a bottomedaxial cavity 21 a that rotatably receives the right end (as viewed inFIG. 2) of the gear shaft 14. When the third main body 21 is mounted tothe second main body 9 of the motor/gear casing 8, the left end (asviewed in FIG. 2) of the boss portion 21 b closely opposes the endsurface of the intermediate gear 15, so that the intermediate gear 15can be restrained from moving along the axial direction between thesecond main body 9 and the third main body 21.

[0037] Terminals 23 a and 23 b (only one terminal 23 a is shown in thedrawings) are attached to the third main body 21 in positions oppositeto the motor 11 in an axial direction substantially parallel to themotor 11 axis. The terminals 23 a are electrically connected to a powersource, e.g., a battery, via electric wires (not shown). The motor 11has terminals 24 a and 24 b (see FIG. 3) corresponding to the terminals23 a and 23 b and adapted to be mechanically and electrically coupled toterminals 23 a and 23 b, respectively, when the third main body 21 ismounted to the second main body 9.

[0038] The third main body 21 may be fixed in position relative to thesecond main body 9 by means of a fixing device, preferably screws (notshown), so that a subassembly 25 can be created which includes themotor/gear casing 8 and the cover 20. Any other appropriate coupling ortightening devices, examples such as a snap-fit mechanism, spring clips,or rivets, may be used in place of screws. In addition, a sealingdevice, preferably an O-ring (not shown) or any other seal member, maybe provided between the motor/gear casing 8 and the cover 20 in order toensure a hermetic seal for the internal elements, which includes thesensor 22, the magnets 19, the gears 13, 15, and 17, and the motor 11,among others.

[0039] The subassembly 25 may be fixed in position relative to the firstflange 3 b of the first main body 3 via fixing devices, preferablyscrews 27. A sealing device, preferably an O-ring 26, may be interposedbetween the flange 3 b and the second main body 9 in order to ensure ahermetic seal for the intake air channel and also to provide protectionfor the internal elements of the subassembly 25, inhibiting dust orother unwanted foreign particles from entering the interior ofsubassembly 25.

[0040] Referring to FIG. 3, an adjusting means, preferably a screw 28,is mounted within the second main body 9 of the motor/gear casing 8 andis positioned to oppose to the throttle gear 17 in a rotationaldirection, preferably in the closing direction of the throttle valve 5.Therefore, as the throttle gear 17 rotates in the closing direction, thethrottle gear 17 contacts one end of the adjusting screw 28, so that thethrottle gear 17 as well as the throttle valve 5 is inhibited fromfurther rotation. The adjusting screw 28 determines the full-closeposition of the throttle valve 5 and advancing or retracting theadjusting screw 28 by manually rotating the adjusting screw 28 cansubsequently adjust the full-close position.

[0041] As described previously, in the representative embodiment thethrottle body 1 includes three separate main parts; the throttle casing2, the motor/gear casing 8, and the cover 20. After associated elementsare mounted onto each of the separate parts, the parts may be assembledtogether to form the throttle body 1. For example, in regards to thethrottle casing 2, the associated elements may include the throttleshaft 4 and the throttle valve 5, among others. In case of themotor/gear casing 8, the associated elements may include the motor 11,the gears 13, 15, and 17, among others. In case of the cover 20, theassociated elements may include the throttle sensor 22, among others

[0042] Because the throttle casing 2 is a separate member apart from themotor/gear casing 8 and the cover 20, the design of a mold that is usedin the molding process of the throttle casing 2 can be optimized toprovide such parameters as substantially uniform thickness of the wallof bore portion 3 a, as well as a uniform thickness of the flanges 3 aand 3 b. Therefore, the unwanted potential deformation of the boreportion 3 a, and the flanges 3 a and 3 b, due to residual molding strainand/or stress, or potential deformation due to heat conducted from themotor 11, can be reduced or minimized.

[0043] In addition, because the second main body 9 of the motor/gearcasing 8 may be made of a material having a high thermal conductivity,the heat of the motor 11 may be effectively dissipated to the outside ofthe motor/gear casing 8. Therefore, overheating of motor 11 and anypossible resultant damage due to the over beating thereof, can beavoided.

[0044] The present invention is not restricted to the embodimentsdescribed above. Various modifications and variations of the aboveembodiments are possible without departing from the scope of the presentinvention. For example, while in the above embodiments the throttlecasing 2 is formed of resin, the throttle casing 2 may also be formed ofsome other material, for example metal. Additionally, the constructionof the throttle sensor 22 is not limited to the constructions depictedin the above-described embodiment; it is possible to adopt various typesof construction.

What is claimed is:
 1. A throttle body comprising: a throttle casinghaving a first main body and a throttle valve disposed within the firstmain body, wherein the first main body is made of resin; a motor casinghaving a second main body and a motor disposed within the second mainbody, wherein the first main body and the second main body are formed asseparate components; and a joint device for joining the first main bodyand the second main body to each other.
 2. A throttle body as in claim1, wherein the first main body includes a substantially cylindrical boreportion that defines a flow channel, in which the throttle valve isdisposed, and wherein the cylindrical bore portion has a substantiallyuniform radial thickness along a circumferential and axial direction. 3.A throttle body as in claim 2, wherein the motor casing is made ofmetal.
 4. A throttle body as in claim 3, wherein the motor casing ismade of lightweight metal.
 5. A throttle body as in claim 4, furtherincluding a coupling device for coupling the throttle valve to themotor.
 6. A throttle body as in claim 5, wherein the coupling device isarranged and constructed to couple the throttle valve to the motor atthe same time that the first main body and the second main body areconnected to each other via the joint device.
 7. A throttle body as inclaim 6, wherein: the throttle casing further includes a throttle shaftthat is rotatably disposed within the first main body and the throttlevalve is mounted on the throttle shaft; the motor casing furtherincludes a gear mechanism for transmitting rotation of the motor to thethrottle shaft, and the coupling device is arranged and constructed tocouple the throttle shaft to the gear mechanism.
 8. A throttle body asin claim 7, wherein the gear mechanism includes a drive shaft thatextends from the second main body, and the coupling device includes arecess and a projection that are formed on one and the other of thedrive shaft and the throttle shaft and are engageable with each otherfor transmitting the rotation of the drive shaft to the throttle shaft.9. A throttle body as in claim 8, further including a cover that has athird main body that is formed as a separate component, apart from thefirst main body and the second main body, wherein the third main body isarranged and constructed to be mounted to the second main body in orderto inhibit communication between the motor and an external environmentoutside of the motor casing, and to inhibit communication betweenassociated internal elements and an external environment outside of themotor casing.
 10. A throttle body as in claim 9, wherein the third mainbody is made of metal.
 11. A throttle body as in claim 10, wherein thethird main body is made of lightweight metal.
 12. A throttle body as inany one of the preceding claims, further including a seal deviceinterposed between the first main body and the second main body in orderto provide a seal therebetween.
 13. A throttle body comprising: athrottle casing having a first main body and a throttle valve disposedwithin the first main body, wherein the first main body is made ofresin; wherein the throttle casing further includes a throttle shaftthat is rotatably disposed within the first main body and the throttlevalve is mounted on the throttle shaft; and wherein the first main bodyfurther includes a substantially cylindrical bore portion that defines aflow channel, in which the throttle valve is disposed, and wherein thecylindrical bore portion has a substantially uniform radial thicknessalong a circumferential and axial direction; and a motor casing having asecond main body and a motor disposed within the second main body,wherein the first main body and the second main body are formed asseparate components; wherein the motor casing further includes a gearmechanism for transmitting rotation of the motor to the throttle shaft,and a coupling device for coupling the throttle shaft to the gearmechanism; a joint device for joining the first main body and the secondmain body to each other; a cover that has a third main body that isformed as a separate component, apart from the first main body and thesecond main body, wherein the third main body is arranged andconstructed to be mounted to the second main body in order to inhibitcommunication between the motor and an external environment outside ofthe motor casing, and to inhibit communication between associatedinternal elements and an external environment outside of the motorcasing.
 14. A throttle body as in claim 13, wherein the motor casing ismade of metal.
 15. A throttle body as in claim 13, wherein the motorcasing is made of lightweight metal.
 16. A throttle body as in claim 13,wherein the third main body is made of metal.
 17. A throttle body as inclaim 13, wherein the third main body is made of lightweight metal.